[linux-lvm] lvm2 confused about double UUID

From: Christian Kujau <lists nerdbynature de>

To: linux-lvm redhat com

Subject: [linux-lvm] lvm2 confused about double UUID

Date: Sun, 26 Jul 2009 17:21:34 -0700 (PDT)

The subject says LVM is confused, but maybe it's me who is confused:
I once had a PV made from a single /dev/sdb and all was well. This sdb
however was really a 2 disk RAID1 which is now split up, the system now
sees both disks, sdb and sdc. Of course, sdb and sdc still have the same
UUID:
# blkid | egrep 'sd[bc]'
/dev/sdb1: UUID="1O2Tkq-9Jy8-VfuZ-uzFh-1f6v-iVBD-hcK6Vq" TYPE="lvm2pv"
/dev/sdc1: UUID="1O2Tkq-9Jy8-VfuZ-uzFh-1f6v-iVBD-hcK6Vq" TYPE="lvm2pv"
I decided to continue to use the VG that was set up on the PV, but since
lvm comlained[0] about finding the same UUID on more than one device, I
tried to instruct lvm to just use sdb for the VG:
# grep filter /etc/lvm/lvm.conf | grep -v \#
filter = [ "r|^/dev/sdc1$|", "r|/dev/.*/by-path/.*|", \
"r|/dev/.*/by-id/.*|", "a/.*/" ]
Now everything looks fine, no more lvm warnings, vg02 seems to use sdb1,
exactly as I wanted:
# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 vg01 lvm2 a- 111.67G 9.27G
/dev/sdb1 vg02 lvm2 a- 931.46G 137.46G
But when I access vg02, I can clearly see I/O to/from sdc! I'd really like
to use sdc for something else now that sdb is used for vg02, but I'm afraid to
do something to sdc, as it still being used - although I don't know why.
Any ideas?
Christian.
# lvm version
LVM version: 2.02.26 (2007-06-15)
Library version: 1.02.20 (2007-06-15)
Driver version: 4.12.0
# uname -r
2.6.24-24-xen <-- Ubuntu/8.04
[0] e.g.
Found duplicate PV 1O2Tkq9Jy8VfuZuzFh1f6viVBDhcK6Vq: using
/dev/disk/by-path/pci-fw1.1-scsi-0:0:0:1-part1 not /dev/sdb1
--
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